COMPLEX RIDDLE

During WWI, there was a bridge connecting Germany and Switzerland. Nobody from Germany was allowed to enter Switzerland, and nobody from Switzerland was allowed to cross to Germany. A guard comes out of his tower every 3 minutes to see if anyone was trying to cross the bridge. If he saw anyone, he told them to go back. A woman in switzerland desperately needed to get to Germany, but knew it would take her at least 6 minutes to cross. But she managed it fine. How?

She started to cross the bridge when the guard went into his tower, got halfway across, and when he came back out she started to go back to Switzerland, the guard assumed she was coming from Germany and told her to go back to Germany.